Telephone-transmitter



(No Model.)

G. W. DRAWBAUGH.

TELEPHONE TRANSMITTER.

Patented May 5,1885.

INVENTOR ATTORNEY N. PETERS. Photo-Lilhognphar. Waning! 0,6.

UNITED STATES PATENT OFFICE.

GEORGE W. DRAWBAUGH, OF EBERLYS MILL, PENNSYLVANIA, ASSIGNOR TO THE PEOPLES TELEPHONE COMPANY, OF NEYV YORK.

TELEPH ONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 317,44c5, dated May 5, 1885.

' Application filed April 25, 1884. (No model.)

To all whom it may concern.-

Be it known that I, GEORGE W. DRAW- BAUGH, of Eberlys Mill, Cumberland county, Pennsylvania, have invented a new and useful Improvement in Telephone-Transmitters, of which the following is a specification.

The invention relates to a telephone-transmitter containing resistance-varying electrodes which are influenced by the vibrations of sound-receivin g plates due to sound-waves produced by the voice to modify a current to render the same suitable for telephonic purposes and it consists in the construction and arrangement of said sound-receiving plates and in the combination ofthe resistancevarying electrodes therewith, as more particularly hereinafter set forth.

In the accompanying drawings, Figure l is a front View of the instrument with portions of the curved sound-receiving plates broken away to show the internal construction. Fig. 2 is a vertical section on the line 3 y of Fig. 1. Fig. 3 is a horizontal section on the line 2 z of Fig. 1. Fig. 4 shows the electrodes separately.

Similar letters of reference indicate like parts.

A is the base or back board.

The case of the instrument consists of the upper piece, B, lower piece, 0, side pieces, D and E, and front piece, F. The upper piece, B, and lower piece, U, may be detachably secured to the baseboard A. Their edges are received in recesses in the side pieces, D and E, which may be detachably secured to said upper and lower pieces, B and G, by screws or other convenient means. The front piece, F, is not recessed, but rests directly against the front edges of the pieces B and G, to which it also maybe detaehablysecured. By this construction the parts of the case may be easily separated and removed, so as to allow of access to the electrodes and internal mechanism of the instrument without disturbing said mechanism.

In the front piece, F, and side pieces, D and E, are formed sound'receiving orifices F, D, and E.

G and H are two sound-receiving plates of metal bent in a curved form, substantially as represented in Fig. 3 of the drawings. The

transverse edges of said plates are bent to form flanges. By the flanges I and J on their inner edges the plates G and H are secured rigidly to the backboard A. To the flanges K and L onthe outer edges of said plates are secured, by solder or otherwise metal brackets M and N. In each of said brackets is placed an electrode preferably consisting of a block of carbon having an inclined inner side. These carbon blocks are shown at O and P. The outer edges of the sound rec'eiving plat-es G and H are not in contact. The upper and lower edges of said plates are received in correspondingly-formed grooves in the upper 5 and lower pieces, B and O, of the case, as shown in Fig. 3. Interposed between the edges of said plates and the bottoms and sides of the grooves are strips R of felt or other yielding elastic material. A piece of felt, S, is likewise interposed between the proximate edges of the soundreceiving plates G and H. The object of these interposed layers of felt is to deaden or stop out the resonant metallic vibrations of the sound-receiving plates due to their normal rate of vibration, and not directly imposed upon them by the air-vibrations due to the voice. The piece S is tightly held between the edges of the plates G and H, and when the several parts of the case are secured in place the strips It are also tightly held between the upper and lower pieces, B and G, of said case and the longitudinal edges of the sound-receiving plates.

By separating the parts of the case as described the strips of felting can be conveniently reached and adjusted.

T is the induction-coil, which is preferably held in a recess formed in the back-board A.

It is sustained in place by a bent bar, U, atv tached to said back-board.- The upper end of this bar is bent over, and upon said end is formed, or to itis attached, a pivot-pin, which enters apertures in the rear arms of a yoke, V, of non-conducting material.

Pivoted between the front arms of the yokepiece V is an electrode, Q, preferably of carbon of prismoidal shape, resting by gravity upon the inclined faces of the electrodes U and P, and forming a bridge between said Ioo electrodes.

Above the yokepiece V is arranged a bar,

WV, which prevents displacement of said yokepiece when the instrument is moved about The circuits in the instrument proceed as follows: From the battery to binding-post 1 by a wire, a, (dotted lines,) on back of baseboard and through the latter to the metal sound-receivin g plate Gr, thence to the electrode 0, thence to the bridge-electrode Q, electrode 1?, sound-receiving plate H, primary wire of induction-coil T, by wire I), to the switch-point o, switch-lever d, binding-post 2, and back to bat tery. The secondary of theinduction-coil communicates with the line binding-posts 3 and 4 by wires 6 e, and by wiresff with the bindingposts 5 and 6, to which a receiving-telephone may be attached.

I claim as my invention- 1. In a telephone, two sound-receivin g plates projecting from and each rigidly secured at one edge to a support and bent or formed so that their opposite free edges are approxt mated, a fixed electrode supported upon each of said plates at or near the approximated edges, the said electrodes not being in contact, and an electrode resting by gravity upon and bridging the fixed electrodes, substantially as described.

2. In a telephone, two sound-receivin g plates projecting from and each rigidly secured at one edge to a support, a fixed electrode at tached to each of said plates, the said electrodes not being in contact, and a movable electrode resting by gravity upon and bridging said fixed electrodes, substantially as described.

3. In a telephone, two sound receiving plates projecting from and each rigidly secured at one edge to a support and having their opposite free edges bent inward to approximate them and then bent outward at right angles to form flanges, the said flanges lying in the same vertical plane, in combination with fixed electrodes attached to each of said flanges and not in electrical contact with each other, and a loose electrode resting by gravity upon and bridging the fixed electrodes, substantially as described.

4. In a telephone, two sound-receiving plates proj ectin g from and each rigidly secured at one edge to a. support and not in contact with each other, a fixed electrode attached to each of said plates, and a loose electrode resting by gravity upon and bridging the fixed electrodes, the said plates being curved, bent, or formed to surround the said electrodes, substantially as described.

5. In a telephone and in combination with resistance-varying electrodes, two sound-reapproximated and a cushion of yielding elastic material interposed between said approximated edges, substantially as described.

6. In a telephone, two sound-receivin plates projecting from and each rigidly secured at one edge to a support and bent or formed so that their opposite free edges are approximated, resistancevaryin g electrodes arranged, substantially as set forth, upon said plates, two platforms attached to the aforesaid supportprojectin g, respectively, above and below said plates, and a layer of yielding elastic material interposed between said platforms and the adjacent edges of said plates, substantially as described.

7. In a telephone, two diaphragms of elastic material projecting from a support and each rigidly secured at one end thereto, a fixed electrode supported by each diaphragm at or near its free end, a third electrode loosely connected to the diaphragm-support between the diaphragms and resting by gravity upon and bridging the fixed electrodes, substantially as described.

8. In a telephone, a support, two sound-re ceiving plates projecting therefrom and secured thereto at one edge, the said plates not being in contact, two platforms projecting from said support, respectively, above and below said plates and at right angles thereto, layers or pieces of yielding material interposed between the proximate free edges of the plates and between the plates and the platforms, and resistance'varyin g electrodes, as described, the said plates being so bent or curved as with the other parts set forth to form a case or covering wholly inelosing the electrodes, substantially as set forth.

9. In a telephone, the combination of the support A, sound-receiving plates G and H, attached thereto, electrodes 0 P, secured to said plates, pivoted electrode Q, yoke-piece V, pivoted or hinged to the support A, and circuit-connections, substantially as described.

10. In a telephone, the combination of the support A, sound-receiving plates G and H, attached thereto, electrodes 0 P, secured to said plates, pivoted electrode Q, yoke-piece V, pivoted or hinged to the support A, and platforms B and O, substantially as described.

11. In a telephone, the combination of the support A, sound-receiving plates G and H, attached thereto, electrodes 0 and I, secured to said plates, pivoted electrode Q, yoke-piece V, platforms B and G, and side pieces D, E, and F, substantially as described.

GEO. IV. DItAVVB AUGH.

XVitnesses \V. R. MURPHY, ORMOND RAMBO.

IIO 

